function isWindow(val) {
  return val === window
} // get nearest scroll element
// https://github.com/youzan/vant/issues/3823

var overflowScrollReg = /scroll|auto/i
export function getScroller(el, root) {
  if (root === void 0) {
    root = window
  }

  var node = el

  while (node && node.tagName !== 'HTML' && node.tagName !== 'BODY' && node.nodeType === 1 && node !== root) {
    var _window$getComputedSt = window.getComputedStyle(node)
    var overflowY = _window$getComputedSt.overflowY

    if (overflowScrollReg.test(overflowY)) {
      return node
    }

    node = node.parentNode
  }

  return root
}
export function getScrollTop(el) {
  var top = 'scrollTop' in el ? el.scrollTop : el.pageYOffset // iOS scroll bounce cause minus scrollTop

  return Math.max(top, 0)
}
export function setScrollTop(el, value) {
  if ('scrollTop' in el) {
    el.scrollTop = value
  } else {
    el.scrollTo(el.scrollX, value)
  }
}
export function getRootScrollTop() {
  return window.pageYOffset || document.documentElement.scrollTop || document.body.scrollTop || 0
}
export function setRootScrollTop(value) {
  setScrollTop(window, value)
  setScrollTop(document.body, value)
} // get distance from element top to page top or scroller top

export function getElementTop(el, scroller) {
  if (isWindow(el)) {
    return 0
  }

  var scrollTop = scroller ? getScrollTop(scroller) : getRootScrollTop()
  return el.getBoundingClientRect().top + scrollTop
}
export function getVisibleHeight(el) {
  if (isWindow(el)) {
    return el.innerHeight
  }

  return el.getBoundingClientRect().height
}
export function getVisibleTop(el) {
  if (isWindow(el)) {
    return 0
  }

  return el.getBoundingClientRect().top
}
